The present invention relates to a course guidance and display apparatus for vehicles. More particularly, it relates to a course guidance and display apparatus for vehicles wherein the traveling locus of the vehicle recorded in a trace device and a map on a film are superposedly projected on a projection screen so as to display the position in which the vehicle exists.
Prior to the application of the present invention, the inventors have developed a course guidance apparatus for vehicles as shown in FIG. 1. The course guidance apparatus for vehicles is arranged, for example, in front of the driver seat of the vehicle. As illustrated in FIG. 1, it is provided with a CRT display 1 and is so constructed that a traveling locus 2 obtained on the basis of detection signals from a direction sensor (not shown) and a speed sensor (not shown) which are separately carried on the vehicle is plotted (or traced) on the screen of the CRT display 1. On the other hand, a map sheet 3 depicted on, e.g., a transparent film is detachably attached to the front of the screen of the CRT display 1. The attached map sheet 3 is fixed by map fixing means 4. At the starting of a drive, the vehicle is caused to travel a certain distance, and the traveling locus is traced. Then, an x-direction, a y-direction and an inclination .theta. are set with a positioning switch 5 so that the traveling locus 2 may extend along a desired road on the map.
The vehicular course guidance apparatus has a major advantageous feature in that by superposing the map sheet 3 on the screen of the CRT display 1, the traveling locus is extended along the road on the map, and it can be expected as one future line of course guidance apparatuses for vehicles. The apparatus shown in FIG. 1, however, uses the CRT display 1 for the tracing of the traveling locus and has on account of the self-luminescence of the CRT display 1 the disadvantage that when the sunlight falls on the screen in the daytime, the CRT display 1 is difficult to indicate a clear traveling locus 2 even with a raised brightness thereof. Another disadvantage is that since the map sheet 3 and the screen of the CRT display 1 are not held in close contact, the map and the traveling locus do not correspond exactly when the CRT display is not viewed frontways. Still another disadvantage concerns the replacement of maps. In a case where a new map is required for, e.g., the reason that the traveling locus has come to the edge of a map in the course of the drive with one map sheet 3 attached, the maps need to be manually replaced. In replacing the maps, a new map sheet 3' to be subsequently attached must be picked out from among a large number of map sheets. Particularly when maps of small contraction scale are used, the replacement of the map sheets is somewhat troublesome. A further disadvantage is that since the CRT display 1 has a considerably large volume, the installation place in the case of mounting the apparatus on the automobile is limited.